With an object detection apparatus which transmits probe waves, receives reflected waves that are reflected from an object, and detects the distance to the object, reverberation is produced when the probe waves are transmitted. The energy of the reverberation is typically significantly greater than the energy of the reflected waves, so that even if the reflected waves are received during a period (reverberation period) in which the reverberation is produced, it is difficult to detect the reflected waves.
An ultrasonic sensor is described in PTL 1, as a sensor which shortens the reverberation period. With the ultrasonic sensor described in PTL 1, after a piezoelectric vibrator is driven, a pulse signal that is of inverse phase to the reverberation is transmitted, and the reverberation is suppressed by the pulse signal.